Demand meter



`lune 25, 1935. J, H- STARK Er AL 2,006,321

DEMAND METER Filed lJune 2O 1934 v- Julian Hbark, Harry M Witherow,

bfg Thei Attorng.

2 aooasai monthis the shaft I4 together with gears I5 and I6 and pointerIl. Pointer I 'I thus corresponds to the usual friction pointer ofprevious demand meters and the approximate demand, as shown by thispointer, is preferably indicated on a scale I8. I9 is a timing motorwhich operates through gear train and timing interval mechanism 2l toreset dog I3 to a zero position every thirty minutes, The same timingmotor 1 ISI operates through a gear train 22 to reset shaft I4 to aAzero position and simultaneouslyadvance the accumulative demandregister I2 at the end of each month when the meter reader presses ashaft 23 axially inward to establish certain driving connectionshereinafter explained.

- The meter reader does not open the meter casing to initiate thisresetting operation, but rather uses a pin 24 which extends through aweatherproof bushing in the front glass cover 25 of the meter. The pin24 is ordinarily sealed or locked in an inoperative condition bysecuring the I hinged part 24 by a seal or lock at hole 26 or 26.

The different registers and pointers are arranged to be read through thefront glass cover of the meter, as indicated in Fig. 2.

Having outlined the main parts of the apparatus, we will now give amoredetailed descrip-f tion 0f the parts and their operative relation. Theinterval demand member or dog I3 is advanced in the direction of ,thearrow through the shaft 30, gears 3I and 32, a friction clutch 33, andgears 34 and 35, from the meter I0. During this advance, a pin 36 in adisc 3'I is rotated in the direction indicated thereon through gears 38.At the end of the thirty-minute interval, a rack 4 0 of the timinginterval mechanism is reciprocated up and down and, in lso doing,rotates an arm 4I, first in a counterclockwise direction and then backagain through part of a revolution. During the first half of thisreciprocating movement,.arm 4I comes against pin 36 and moves itcounterclockwise to a zero position` and, at the same time, dog I3 ismoved clockwise to a zero position, the friction clutch at 33 permittingthis resetting operation. The .return'movement of arm 4Iuto the positionshown brings it out of the -way and allows the free advance of pin A36'n a clockwise direction towards arm 4I during the next demand interval.

' .The timing interval mechanism 2| which is driven by timing motor I9through geartrain 20 will next be explained. The disc at 42 is drivenfrom the gear train 20 at a constant speed l in a clockwisel directionat one revolution in thirty minutes and, in so doing, it drives a shaft43 and winds up a spring 44. Spring 44 has one end secured in driving.relation with shaft 43 and the other end secured to a gear 45. Gear 45is secured to a-hollow-shaft 46 on which is mounted an-eccentric 41 anda disc 48, all-free to turn as a unit on shaft 43. However, the hollowshaft 46 and theparts carried thereby are normally blocked from'rotationin a clockwise direction as urged by spring 44 because' of a stop arm 49pivoted on the side of discl 48 and resting on a. stop plate 50.

Once' during 'each revolution 'of disc 42, a finger 5|,.which rotates'with shaft 43 with a slight lost motion permitted by play between pins 5I comes against the outer underside of stop arm 49', moves it upward-'and off of stop plate 50, and releases the hollow-shaft 46, allowing itto rotate a complete revolution under the tension of spring 44 atwhichtime the stop arm 49 is again brought against stopplate 50 and preventsfurther rotation until another thirty-minute interval vhas passed. Asecond governor Ill is geared to gear 45 to limit the speed of and theshock of stopping the rotation of hollow shaft 46 and the parts carriedthereby. Thus, periodically, once every thirty minutes, which is thedemandv interval selected, eccentric 4l makes one complete revolution inabout one second and, in so doing, oscillates the follower 52 and rack46 which is connected to the follower. In this way, the dog I3 isquickly and accurately returned to a zero position every thirty minutes.

During the advance of dog I3, it will come against an arm 53 projectingfrom shaft I4 if this arm is not already in a position beyond which thedog I3 is advanced during any given demand interval and which, whenadvanced, rotates shaft I4, gears I5 and I6, and pointer I'I up scale.When the dog I3 is reset to zero, the parts connected between shaft I4and pointer Il ordinarily remain in the advanced position. As a result,the position of these parts will represent a measurement of thethirty-minute interval maximum demand over any desired period of time,such as a month. At the end of the month or at the end of such otherperiod when the meter readings are taken, the meter reader records thereadings of dials I I and I2 and itis then desirable to reset the partscorresponding to the maximum demand to a zero position. These are theparts 53, I4, I5, I6, and Il, and, in order to do this, the dog I3 mustlikewise be reset to zero with arm 53 in contact therewith. To do this,the seal I3 in opening 26 (shown in Fig. 2) is removed, part 24' israised until it is in line with pin 24 and then it is pushed inwardagainst the end of shaft 23 kwhich is telescoped into the end of shaftI4. Shaft 23 carries a gearu 54 which is fastened thereon and which hasa front pin 55 normally resting in a short slot in the stationary plate64 of the meter and a rear pin 56 projecting part way towards gear I5.Gear 54 has a small portion 5l on its inner periphery Where the teethare cut away and, in the position shown, the continuously-rotating gearl58 driven from the timing motor I9, in the direction indicated by thearrow, is prevented from driving gear 54 by reason of the mutilatedportion 5l of this gear.

Gear 54 is normally retained in the axial position shown, out of meshwith gear 58, by a spring 59 which is under compression between a collaron the outer end of shaft 23 and the plate 64 which rotatively supportsthis shaft. However, when the pin 24 is pushed inward, shaft 23 and theparts thereon are moved in an axial direction to remove pin 55 from itsslot, to mesh the gears 54 and 58, and to move pin 56 towards gear I5and into the path of rotation of a pin 60 on the front face of gear I5.This endwise movement of shaft 23 also causes its rear pointed end toengage the inner end of the recess in the forward end of shaft I4 andshaft I4 and gear I5 are moved endwise in the same ydirection by alesser amount but sufficient to engage a friction clutch, one part 6I ofwhich is on the rear face of gear I5 and the other part 62 of which ison a gear member 63 in driving engagement with the accumulative demandregister I2.

Continuously-rotating gear 5B is now in driving iii) Adisengaged fromgear 5B.

acodeai endwise and the driving connection between gears 54 and 58 isbreiten due to the mutilated portion 51 of gear iil again registeringwith gear 58. As gear 54 and the 55 projecting from its rear surfacerotate in a clockwise direction one revolution, gear iii is not driventherewith until or unless pin engages with pin 56. These pins Willengage during this operation unless gear i5 is in a zerodemand-indicating position and, ii not in this position, the operationwill drive gear i5 and the parts are connected thereto to a zerodemand-indi `ting position which is the polsition where pin registerswith the forward end of the slot in plate S and gear 5d is about to "neAlso, this zero de mand-indicating position is where the pointer il isat the Zero end ci its scale iii. The idle position of gear 5d isindicated by a pointer tii on the outer end of shaft 2d and is in viewof the meter reader and from which he may ascertain when the resettingoperation starts and when complated.

When gear i5 is driven to a zero-indicating position or reset by energyreceived from the timing motor i9, the dog i3, shaft 3i), gears 3l, and38, and the disc 31 with its pin 35 will also be driven to a Zeroposition'i they do not happcnto be in such position. VThis is permittedby the friction clutch at Both resetting operations are performed byenergy received from the timing motor i9. in the case of thedemand-interval reset, the energy is rst stored in the spring M andreleased at intervals and, in the case of the rnaximuni-demand-intervalreset, Ithrough gear train 22, the energy being received directed frommotor iii. The two mechanisms are sulciently independent, however, thatthey may perform their resetting operations at the same -or difiercnttimes without interference.

When the maximumdemand-interval reset, which is initiated by the meterreader, occurs, it was pointed out above that the parts 6l and 52 of thefriction clutch between gear i5 and the accumulative demand register i2were in engagement and, as a result, the maximum-demand measurement,corresponding to the amount gear l5 and pointer i1 are reset isregistered on the dial type register l2 and is added to any previousamount which this register indicated. After the maxiu mum-demand reset'has occurred, register l2 is read again and the exact maximum demandfor the previous month is obtained by subtracting the reading beforereset from the reading after reset. The result should correspond toVwhat was indicated by the pointer l1 on the scale I8 prior to theresetting operation although it is possible to read the register I2 witha greater degree of accuracy. The indication given by pointer I1 beforereset thus serves as a check on the proper operation of the resettingmechanism.

A spring 6i! assures that the friction clutch parts 6I and 62 will lbedisengaged as soon as this is permitted by the registration of pin 55with its slot in plate 64 at the end of this resetting operation. and afriction member 6'9 is preferably secured between gear 63 and plate 10to prevent overshooting and accidental rotary movements of the rotatingparts of dial mechanism l2 except as positively driven in a resettingoperation. The reason for providing a short slot instead of merely around hole in plate S4 for the reception of pin 55 is kto permitsufiicient rotation of gear 54 when in the axial position shown ior pin56 to pass pin 50 after pin 50 has been driven to its zero positionimmediately following a resetting operation and the pins are of suchlength that this is possible when gear 5|! is in the position shown,moved away from gear l5. ln actual practice, the parts 5d, Si, 62, and53 are much more closely spaced and the pins 55 and Ell are very muchshorter than here represented. In fact, although distorted in theillustration, the plates 64 and 10 are the central'and back plates ofthe main meter register ii.

fi safety stop 56 is preferably provided against which a projection 65in gear i5 will be driven .in case the parts do not disengage at thezero position. This stop arrangement consisting of pin 66 and projection65 is merely a safety arrangement and ordinarily when the parts are returned to zero, projection 55 does not quite reach stop pin t6. However,if something should go wrong with the declutching operation such aswould tend to drive the gear i5 and register i2 continuously, theprojection 55 cornes against stop pin 56 and stalls the timing motor.This is preferable to destroying the accumulated record. possiblycausing damage to some deiicate part of the mechanism.

illustrated, the :hammurn-dernami-nicasu urement parts connected withgear i5 are shown to be advanced from a aero position over aboutone-hali of their complete range ci movement. Likewise, theinterval-demand dog i3 and parts connected thereto are shown advancedfrom a aero position in about the same proportion, the demand-intervalmechanism 2i will trip in about ten minutes assuming a thirtyrnlnuteintervai since pin 5i has completed about two-thirds of revolutiontowards the releasing position a-:ljaW centstop plate 50.

It will be assumed that the timing motor is synchronous timing motor andthat its terminal shaft 1l makes one revolution per minute. The geartrain 20 is then a speed-reducing train of 3U to l. We have found itpracticable and convenient to have the gear 54 malte one revolution inabout one minute when a maximum-demand resetting operation is performedand the gear drive between the terminali shaft 1i and gear 54 may,therefore. have a l to l ratio although this is not essential. We alsoprefer to provide an overrunning clutch 12 between the timing motor andgear trains to facilitate testing of the device in the factory and atother times as desired. This overrunning clutch simply allows the motorto drive the gear train in the usual way and also allows the gear trainto berun in the same direction as before without running' the motor, orat a faster rate than it would be driven by the motor if the latter isrunning. When the meter is removed from its casing, gear trains 22 and29 may be manually advanced to test out the maximum-demand-resettingoperation.

Having described the mechanism, it may be helpful to briefly review aresetting operation of the maximum-demand apparatus as initiated by ameter reader. The meter reader rst takes down the readings of dials liand i2, notes the reading of pointer i1, and records it also ifrequired. He then removes the seal 13 (Fig. 2.), raises the hinged part24 until in line with pin 24, and presses gently inward until he seespin 61 start to rotate. He then withdraws pin 2|,

Ziix

till

turns part 24 down to the locking position, and seals it in place. Bythat time, he notes that pointer 61 has completed its revolution andpointer I'I has returned to zero and he takes down the new reading ofregister I2. The difference in the two readings of register I2 shouldcheck approximately with the initial reading on dial I1.

.As soon as the operation is initiated by movement of shaft 23 to therear, the following operations take place. Gear 54 meshes with gear 58and is driven in a clockwise direction, pin 55 bears against the innerside of plate 64 and holds the shaft 23 and the other parts which areaxially `displaced to the rear in their axially-displaced positionsuntil the resetting ,operation has been completed. Gear l is also movedaxially to the rear to engage the clutch parts 6I and 62 but thismovement is somewhat less than the axial movement of shaft 23. Gear I5and the parts including register E2 do not rotate until pin 55 comesagainst pin 60, after which all of these parts are driven to a zeroposition. At the same time that gear I5 reaches the zero position, pin55 registers with its slot in plate 64 and gear 54 is moved axially tothe front, disengaging pin 5S from pin 60 and disengaging clutch parts5I and 62. Gear 54 is then driven a very small distance further beforelosing its driving connection with gear 58. This causes gear 54 torotate the small amount permitted by the'slot in which pin 55 is nowreceived and this carries pin 56 beyond pin 60 ready for anotherresetting operation, even though pin 60 remains in its zero position.

Aside from thegreater accuracy of reading the maximum demand with theaccumulative register I2, the registration of maximum demand in this wayhas certain advantages which may be exemplified by considering a fewtypical readings taken from the register I2 as they might appear in themeter readers book, thus- Demand register 12 Maximum de- Meter register1.1 mand for past Before re- After remonth setting setting It will beobserved that the reading of the register I2 remains unchanged duringthe month between meter readings and maximum-demandresetting operations.This provides a check by means of which the meter reader can see at aglance if the previous record was correctly taken down or if the.register I2 has been changed by some unauthorized person during themonth. There is little danger of a dishonest meter readers turning infaked readings as each reading is` available for checking for a wholemonth by the power company and by the customer. same reason,a dispute asto the correctness of the maximum-demand reading on which a bill isbased may be readily checked prior to the time the customer wouldordinarily pay such billi. Since the Imaximum-demand reset is notperformed manually, the difficulties that arise incident to the manualadjustment of delicate mechansm by unskilled persons are avoided andtheoperation is less dependent upon human Judgment.

In this form of demand meter, the person who For the initiates themaximum-demand-resetting operation does not need to open the meter.Nevertheless, he must be an authorized meter reader as the pin 24/cannotbe pushed in until the seal at 26 is removed and the part 24' is raisedbecause, when this is down in the position shown in Fig. 1, pin 24 islocked from movement in either direction, and where it also blocks theopening in the meter cover so that no other pin can be inserted.

Although we have described the invention in connection with themeasurement of electric energy, it will be evident that,` so far as theinvention is concerned, gear 34 might be driven by or otherwise advancedin accordance with any device, the maximum demand of which it is desiredto investigate. Since the timing interval mechanism 2 i performs itsoperation quite independently of ther maximum-demand-reset mechanism,the former need not be of the type herein described nor is it essentialthat the power used to reset the maximum-demand mechanism be obtainedfrom the existing timing motor although this is highly desirable when itis appreciated y that all of the parts including the watt-hour meter I0are intended to be contained within a meter casing of the usual housetype sizeas indicated in Fig. 2.

What we claim as new and desire to secure by Letters Patent in theUnited States is:

l. A Ademand meter comprising an intervaldemand member which is advancedover predetermined intervals of time in accordance with a measurementand periodically reset to a zero position at the end of such intervals,a maximumdemand part which is advanced from a zero position inaccordance with the maximum advance of the interval-demand member overmany of said time intervals, and means for setting the maximum-demandpart to a zero position comprising terval member which is advanced froma zero position over predetermined intervals of time in accordance witha measurement and reset to such zero position at the end of said timeintervals, a maximum-demand part which is advanced from a zero positionin accordance with the maximum advance of the interval member over manyof said time intervals, and means for resetting said maximum-demand partto its zero position comprising a motor-operated gear, a second gearnormally disengaged from the motor operated gear, manual means forinitially engaging said gears, means forautomatically disengaging saidgears after the normally-disengaged gear has made one revolution, andmeans driven by said last mentioned gear during such revolution fordriving said maximum-demand part to its zero position.

3. A demand meter comprising an interval-demand member which isperiodically advanced from a zero position in accordance with ameasurement and returned to its zero position at the end ofpredetermined time intervals, a maximumdemand part which is advancedfrom a zero position in accordance with the maximum advance of saidinterval memberl over many of said time intervals, and means forreturning said maximum-demand part to its zero position comprising anormally-stationary gear, a normally-driven gear, manual means formoving the normallystationary gear in an axial direction to drivingengagement with the normally-driven gear, means for retaining said gearsin such engagement while the normally-stationary gear makes one completerevolution and then automatically disengaging said gears by a reverseaxial movement of the normally-stationary gear, and means operated bythe normally-stationary gear during such revolution for driving saidmaximum-demand cart to a zero position.

4.. .A demand meter comprising an intervaldemand member advanced from aaero position over predetermined time intervals in response to ameasurement, a timing motor and means operated by said motor forreturning said demand member to its zero position at the 'end of eachsuelo ie interval, a maximum-demand part which is advanced from a zeroposition in accordance with the maximum advance of tbe intervaldemandmember over many time intervals, and manually-controlled means operatedby said timing motor for driving said maximum-demand nait to its zeroposition.

5. i demand meter having a periodically reset dog which is advanced inaccordance with a measurement and automatically returned to a aeroposition at predetermined time intervals, a maximum-demand part which isadvanced from a aero position in accordance with the maximum ad ice oi'said dog over many ci said time intei als, and a mot-or for establishingsaid time intervals and for returning said dog and said man mum-demandparts to their zero positions, l operated means ior initiating ticleiurn-defznand member to its "ming 'mo-tor.

r comprising an intervala :iemand emand member' which is advanced from azero position over predetermined time intervals in accordance with ameasurement, a maximum-depart v/nicn advanced. from a zero position inaccordance vv"'li the ma; 4drum advance oi' the interval-demand memberover many such time intervals, means for automatically returning theinterval-demand part to its aero position at the end of each of tirepredetermined intervals, means controlled manually for returning tloemaximumdemand part 'to .its zero position when desired, and. a commontiming motor for operating both of said zero-returning means.

7. A maximum-demand meter comprising an interval-demand member' which isadvanced from a zero position in `accordance with. a measurernent overpredetermined time intervals and reset to a zero position at the end ofsuch time intervals, a maximum-demand part which is advanced from a aeroposition in accordance with the maximum advance of the interval-demandmember over many time intervals, a normally idle accumulatingregister, aconstantly-operating motor and manually-controlled means forestablishing a driving connection between said maximum-demand part, saidregister and said motor for returning the maximum-demand part to itszero position and registering the maximum demand measure thereby on saidregister.

8. A demand meter comprising an interval-demand member wtiicii advancedfrom a zero position in accordance with a measurement and returned toits sere oosition at the end ci predetermined time intervals, amaximum-demand part which is advanced from a zero position in accordancewith tine maximum advance o the interval-demand member over many of suchtime intervals, a constantly-operating timing motor for establishingsaid time intervals, a normally-idle accumulating register andmanually-controlled means for establishing a driving connection betweensaid maximum-demand part, said accumulating register and said timingmotor for returning the maximum-demand part to its zero position andregistering the maximum demand measured thereby on said register, andmeans for thereafter automatically interrupting said driving connection.

9, In a maximum-demand meter, a rotativelymountedmaximum-demand-measuring :cart which is advanced from a zero position inaccordance with tlie maximum demand as measured over many timeintervals, a normally-stationary rotary member in axial alignment vvitrLsaid de mand-measuring part, said demand-measuring part and saidnormally-stationary rotary member being movable axially,aconstantly-rotating member adjacent said normally-stationary rotarypart, an accumulating register having a driving member closelyassociated with said demandmeasuring part, resilient means normallyretaining said demand-measuring part, said normallystationary part, saidconstantly-rotating inember, and said register-driving member out ofdrivm ing relation with each other, and manually-operated means formomentarily axially displacing said normally-stationary part and saiddemand-s measuring part to establish driving connections between themand with said closely associated members for returning said demand-measing part to a zero position and for adding its measurement to saidregister, and resilient means for c the axially-displaced tovigiositions as soon as said operations are completed,

lo. a sealed casing, demand meter comprising a maximum mand-measuringpart, interval-demand-measuiing means for positioning sai cart away aaero-measurement position i accordance with maximum demand as measuredover many equal time intervals, normally-inactive motor-operated meansfor automaticalli7 resetting said maximum-demandmeasuring part to itszero position, a nin extending through a wall of said casing, 'd ninhaving' limited endwise movement 'for intiating suoli resettingoperation, and means external to said casing for sealing said pin in acondition wliere it cannot be used to initiate such resetting operation.

ll. A sealed casing, a meter contained within said casing including amaximum-demand-measuring part which is moved away from a aero positionin accordance with the maximum demand as measured over a plurality oiequal time intervals, a constantly-operating motor for establishing saidtime intervals, a normally-inactive accumulative register,normally-disengaged driving connections between saidmaximum-demandmeasuring part, said motor and said register which whenestablished causes said motor to return the maximum-dernand-measuringpart to a zero position and to add its measurement to said register andthereafter interrupting said driving connections, a pin extendingthrough a wall of said casing movable from a first position to a secondposition to establish said driving connections, and means external tosaid casing ior sealing s pin in the first mentioned position.

l2. A demand meter comprising an intervaln demand member which isadvanced from a aero position in accordance tvitn a measurement overpredetermined intervals of time and reset to its zero position at theend of such intervals, a. maximum-demand-measuring part which ilsadvanced from a zero position in accordance with the maximum demand oi'the interval-demand member over many o1' such time intervals, a timingmotor and means driven thereby for automatically returning saidintensi-demand member to a zero position at the ends of said predel0termined time intervais `manually-controlled vmeans driven by said motorfor returning said maximum-demand part toits zero position when desired,and an overrunning vclutch betweenl said motor and the above mentionedarts which are driven thereby, whereby the parts normally driven by saidmotor lmay be operated manually, independently of said motoig

